ABCMdb

PMID: 18325934

Frelet-Barrand A, Kolukisaoglu HU, Plaza S, Ruffer M, Azevedo L, Hortensteiner S, Marinova K, Weder B, Schulz B, Klein M
Comparative mutant analysis of Arabidopsis ABCC-type ABC transporters: AtMRP2 contributes to detoxification, vacuolar organic anion transport and chlorophyll degradation.
Plant Cell Physiol. 2008 Apr;49(4):557-69. Epub 2008 Mar 6., [PubMed]

Sentences

No. Mutations Sentence Comment

13 ABCC7 p.Glu217Gly Abbreviations: ABC, ATP-binding cassette transporter; ABRC, Arabidopsis Biological Resource Center; Bn-NCC-1, Brassica napus non-fluorescent chlorophyll catabolite 1; BPT1, bile pigment transporter 1; BSA, bovine serum albumin; CDNB, 1-chloro-2,4-dinitrobenzene; CFTR, cystic fibrosis transmembrane conductance regulator; DNB, dinitrobenzene; DTT, dithiothreitol; E217G, 17b-estradiol 17-(b-D-glucuronide); GFP, green fluorescent protein; GS, glutathione; GS-X, glutathione conjugate; GUS, b-glucuronidase; LTC4, leukotriene C4; NASC, Nottingham Arabidopsis Stock Center; MRP, (ABCC) multidrug resistance-associated protein; NBD, nucleotide-binding domain; ORF, open reading frame; PAR, photosynthetically active radiation; PGP, P-glycoprotein; RT-PCR, reverse transcription-PCR; TMD, transmembrane domain; TWD1, twisted dwarf 1; UTR, untranslated region; YCF1, Yeast cadmium factor 1. Login to comment 49 ABCC7 p.Glu217Gly Interestingly, AtMRP1 and AtMRP2 but not members of clade II physically interact with the C-terminal tetratricopeptide repeat domain of the membrane-bound FKBP-like immunophilin TWD1 (TWISTED DWARF1) which agrees with a modulation of vacuolar metolachlor-GS and 17b-estradiol 17-(b-D-glucuronide) (E217G) uptake by recombinant TWD1 (Geisler et al. 2004). Login to comment 112 ABCC7 p.Glu217Gly Col-6 mesophyll vacuoles possessed ATP-dependent transport activities for the organic glucuronide E217G which appears in the mammalian liver during steroid degradation, as already demonstrated for a variety of mono-and dicotyledonous plants (Table 1; Klein et al. 2006). Login to comment 113 ABCC7 p.Glu217Gly Efficient inhibition of vacuolar E217G uptake by vanadate confirmed that transport occurred via an ABC transporter. Login to comment 114 ABCC7 p.Glu217Gly In contrast, E217G uptake was significantly reduced to about 70% when vacuoles were isolated from atmrp2-1 plants (P50.05). Login to comment 122 ABCC7 p.Glu217Gly Previous studies using isolated rye and barley vacuoles and the characterization of transport activities of heterologously expressed AtMRP2 demonstrated that transport of glucuronides such as E217G is strongly stimulated by DNB-GS (Klein et al. 1998, Liu et al. 2001). Login to comment 153 ABCC7 p.Glu217Gly ABCC7 p.Glu217Gly Thus, either a clade II AtMRP has the Table 1 ATP-dependent uptake of [3 H]estradiol 17-b-D-glucuronide (E217G) or [3 H]leukotriene C4 (LTC4) into rosette leaf mesophyll vacuoles isolated from atmrp2-1 and its corresponding wild type (Col-6/gla1) in the presence of MgATP Line/treatment Transport into isolated mesophyll vacuoles [pmol Â (ml vacuolar volume Â min)À1 ] Substrate E217G LTC4 Col-6/gla1 0.82 Æ 0.10 (100%) 308 Æ 71 (100%) Col-6/gla1 þ 1 mM vanadate 0.15 Æ 0.03 (18%) 18 Æ 6 (6%) Col-6/gla1 þ 0.2 mM DNB-GS 0.65 Æ 0.07 (79%) n.d. atmrp2-1 0.55 Æ 0.10 (67%)Ã 175 Æ 24 (57%)Ã atmrp2-1 þ 1 mM vanadate 0.10 Æ 0.05 (12%)Ã 11 Æ 5 (3.5%)Ã atmrp2-1 þ 0.2 mM DNB-GS 0.43 Æ 0.08 (53%)Ã n.d. In the absence of AtMRP2, ATP-dependent organic anion transport rates are reduced to 60-70%. Login to comment 186 ABCC7 p.Glu217Gly Reduced vacuolar transport activities in the atmrp2-1 mutant The ATP-dependent, vanadate-sensitive vacuolar transport activities for the glutathione conjugate LTC4 and the glucuronide E217G-two model substrates for MRP/ABCC-type transporters-were reduced to 60 and 70%, respectively, when mesophyll vacuoles isolated from atmrp2-1 were compared with the corresponding wild type vacuoles (Table 1). Login to comment 193 ABCC7 p.Glu217Gly Interestingly, Arabidopsis mesophyll vacuoles did not display indications of cross-stimulation of organic anion transport since transport of E217G was not stimulated by the GS-conjugate DNB-GS in our experiments. Login to comment 261 ABCC7 p.Glu217Gly Unless indicated otherwise, for each time point and condition five polyethylene tubes (0.4 ml capacity) were prepared as follows: 70 ml of medium G [22% (v/v) Percoll, 0.4 M sorbitol, 30 mM KCl, 20 mM HEPES-KOH, pH 7.2, 0.12% (w/v) BSA, 1 mM DTT] containing 1 mM MgSO4 (without ATP) or 6 mM MgSO4 and 5 mM ATP (with ATP), and substrates (0.2 mCi of [3 H]E217G and 10 mM E217G or 20 nCi (1.27 nM) of [3 H]LTC4) and further substances as indicated were placed on the bottom of the tube. Login to comment